Prepreg and method for manufacturing same

Abstract

The present invention provides a prepreg comprising: a primary pre-pregnant made of a reinforced fiber substrate and an epoxy resin composition containing at least epoxy resin and thermoplastic resin impregnated into the reinforcing fiber that forms the reinforced fiber substrate; and a surface layer made of epoxy resin composition containing at least an epoxy resin and an epoxy resin-soluble thermoplastic resin that dissolves in the epoxy resin, the surface layer being formed on one or both surfaces of the primary prepreg; the prepreg being characterized in that only one of either the epoxy resin composition of the primary prepreg or the epoxy resin composition of the surface layer contains a hardening agent for an epoxy resin.

The invention claimed is: 
     
       1. A prepreg comprising:
 a primary prepreg composed of a reinforcing fiber substrate and an epoxy resin composition containing at least an epoxy resin in uncured state which can be cured by a reaction with a curing agent, and 5 to 50 mass parts of an epoxy resin-soluble thermoplastic resin relative to 100 mass parts of the total epoxy resins used in the prepreg, dissolved in the epoxy resin, impregnated into a reinforcing fiber layer formed by the reinforcing fiber substrate, and 
 a surface layer composed of an epoxy resin composition containing at least an epoxy resin in uncured state which can be cured by a reaction with the curing agent, and an epoxy resin-soluble thermoplastic resin dissolved in the epoxy resin, the surface layer being formed on one side or both sides of the primary prepreg, 
 wherein only either of the epoxy resin composition of the primary prepreg and the epoxy resin composition of the surface layer contains the curing agent for epoxy resin in an amount appropriate to cure the total amount of the epoxy resins contained in the prepreg. 
 
     
     
       2. The prepreg according to  claim 1 , wherein the epoxy-resin-soluble thermoplastic resin is at least one kind selected from polyethersulfone, polysulfone, polyetherimide and polycarbonate. 
     
     
       3. A prepreg comprising:
 a primary prepreg composed of a reinforcing fiber substrate and an epoxy resin composition [A] impregnated into a reinforcing fiber layer formed by the reinforcing fiber substrate, and 
 a surface layer composed of an epoxy resin composition [B], formed on one side or both sides of the primary prepreg, 
 wherein: 
 the epoxy resin composition [A]: is an epoxy resin composition containing at least an epoxy resin in uncured state which can be cured by a reaction with a curing agent, the curing agent for epoxy resin in an amount appropriate to cure the total amount of the epoxy resins contained in the prepreg, and 5 to 50 mass parts of an epoxy-resin soluble thermoplastic resin relative to 100 mass parts of the total epoxy resins used in the prepreg, dissolved in the epoxy resin, and 
 the epoxy resin composition [B]: is an epoxy resin composition containing at least an epoxy resin in uncured state which can be cured by a reaction with the curing agent, and an epoxy resin-soluble thermoplastic resin dissolved in the epoxy resin but containing no curing agent for epoxy resin. 
 
     
     
       4. The prepreg according to  claim 3 , wherein at least 30% by mass of the total amount of the epoxy resins contained in the epoxy resin composition [A] and the epoxy resin composition [B] is a tri-functional epoxy resin. 
     
     
       5. The prepreg according to  claim 3 , wherein the epoxy resin composition [A] further contains an epoxy resin-insoluble thermoplastic resin. 
     
     
       6. The prepreg according to  claim 5 , wherein the epoxy resin-insoluble thermoplastic resin is at least one kind selected from amorphous nylon, nylon 6, nylon 12 and amorphous polyimide. 
     
     
       7. The prepreg according to  claim 3 , wherein the curing agent contained in the epoxy resin composition [A] is an aromatic diamine compound. 
     
     
       8. The prepreg according  claim 7 , wherein the aromatic diamine compound is 3,3′-diaminodiphenylsulfone. 
     
     
       9. The prepreg according to  claim 7 , wherein the aromatic diamine compound is 25 to 55 parts by mass relative to 100 parts by mass of the total epoxy resin used in the prepreg. 
     
     
       10. The prepreg according to  claim 3 , wherein the amount of the curing agent for epoxy resin is 60 to 100 parts by mass relative to 100 parts by mass of the epoxy resin contained in the primary prepreg. 
     
     
       11. A method for manufacturing a prepreg, which comprises:
 impregnating an epoxy resin composition [A] into a reinforcing fiber layer formed by a reinforcing fiber substrate to obtain a primary prepreg, 
 then, placing, on one side or both sides of the primary prepreg, an epoxy resin composition [B] to make the epoxy resin composition [B] integral with the primary prepreg, wherein: 
 the epoxy resin composition [A]: is an epoxy resin composition containing at least an epoxy resin in uncured state which can be cured by a reaction with a curing agent, the curing agent for epoxy resin in an amount appropriate to cure the total amount of the epoxy resins contained in the prepreg, and 50 to 50 mass parts of an epoxy resin-soluble thermoplastic resin relative to 100 mass parts of the total epoxy resins used in the prepreg, dissolved in the epoxy resin, and 
 the epoxy resin composition [B]: is an epoxy resin composition containing at least an epoxy resin in uncured state which can be cured by a reaction with the curing agent, and an epoxy resin-soluble thermoplastic resin dissolved in the epoxy resin but containing no curing agent for epoxy resin.